In general, for example, a semiconductor wafer manufacturing process, a photolithography technique is used to form a pattern of a resist film on a surface of a substrate to be processed such as a semiconductor wafer or an LCD substrate. Such a photolithography technique includes a resist coating process which coats a resist solution on the surface (upper surface) of the substrate to be processed, an exposing process which exposes a pattern on the resist film with the resist solution coated thereon, and a developing process which supplies a developer on the substrate to be processed after the exposing process.
In this case, the resist coating process supplies (drops or discharges) the resist solution on the surface of the substrate to be processed under rotating, and forms the resist film on the surface of the substrate to be processed by virtue of a centrifugal force. As such, a thickness of the resist film in a peripheral portion of the substrate to be processed becomes thicker, thus causing a poor film thickness uniformity of the surface of the substrate to be processed. In addition, in the course of transferring or processing the substrate to be processed, a surplus resist film residing the peripheral portion is stripped away, which causes particles.
To overcome this problem, there is a technique which forms the resist film on the surface of the substrate to be processed, exposes the peripheral portion of the substrate to be processed, and removes the surplus resist film residing the peripheral portion of the surface of the substrate to be processed by the developing process. In such a technique, a heating treatment is performed to evaporate and remove a residual solvent from the resist film, which causes a variation in characteristic of the resist film depending on a heating temperature. Specifically, it is found that a resist droop, which represents that a cross section of the resist film which is formed by the removal process is smoothly inclined, occurred, and also a width of the resist droop is varied depending on the temperature of the substrate to be processed at the beginning of the peripheral exposure treatment.
Hence, in order to surely remove the surplus resist film by exposing and developing the peripheral portion of the substrate to be processed, there is need to control the temperature of the exposure region of the substrate to be processed.
As an apparatus which exposes the peripheral portion of the substrate to be processed in a state where the temperature of the resist film formed on the surface of the substrate to be processed is controlled, there has been known a peripheral exposure apparatus which includes a temperature controller installed at the rear side (lower surface) of the substrate to be processed. In the conventional peripheral exposure apparatus, the temperature controller includes a cooling mechanism which cools the substrate to be processed by blowing a cooling fluid. The temperature controller controls the cooling mechanism such that the temperature of the peripheral portion of the surface of the substrate to be processed is controlled.
However, the conventional peripheral exposure apparatus controls a temperature of the exposure region of the surface of the substrate to be processed performing at the lower surface side. As such, when a thermal capacity of the substrate to be processed is lager, in case of a wafer which has a diameter of 450 mm and has a thermal capacity of 2.7 times larger than, e.g., a conventional wafer having a diameter of 300 mm, a time is required to control a temperature of the resist film formed on the surface of the substrate to be processed to a predetermined temperature. This causes a decrease in efficiency of the peripheral exposure treatment.